Electric clock and system



Dec. 31, 1935. H. E. WARREN ELECTRIC CLOCK AND SYSTEM Filed Feb. 16

lnvntor Henry E. W \"1'" n, bl 7+ His Attorney.

Patented Dec. 31, 1935 UNITED STATES PATENT OFFICE ELECTRIC CLOCK AND SYSTEM corporation of Maine Application February 16, 1934, Serial No. 711,567

11 Claims.

My invention relates to electric clock installations which are particularly suitable for use on ocean-going ships, such as naval vessels although not limited to such use. In an installation of 5 this character, it is important that all the clocks of the system shall read exactly alike and be capable of being quickly and accurately reset from a central control point. These and other objects are accomplished in accordance with my invenl tion preferablythrough the utilization of synchronous clock-setting motors in combination with special control features therefor.

The features of my invention which are believed to be novel and patentable will be pointed out in 16 the claims appended hereto. For a better understanding of my invention, reference will be made in the following description to the accompanying drawing, Fig. 1 of which represents an exploded view of the principal parts of a clock embodying 20 my invention; Fig.2 is a face view of such a clock; and Fig. 3 represents a clock system and control circuits using the type of clock represented in Fig. 1. The clock mechanism represented in Fig. 1 in- 25 eludes, in addition to the synchronousmotor I!) for normally operating the clock hands, two additional synchronous motors H and I2, one for quickly setting the clock hands ahead and one for quickly setting the clock hands backward. An 30 electromagnetic stop device I3 is also provided for stopping the clock hands in certain definite positions for use when it is desirable to assure that all elocks of the system indicate the same. The synchronous motor ill for normally driving the clock 35 is preferably provided with an electromagnetic signal device 94 for indicating failures of power. Provision is made at l5 for manually setting the clock hands with a special key. Suitable gear drives and the necessary clutches are provided be- 40 tween the different motors and clock hands as will presently be explained in detail. The entire block mechanism is preferably placed in a water- 'tight clock casing which may be sealed or locked to prevent unauthorized access thereto.

Referring now to the detail construction of the clock of Fig. l, I will first explain the drive from the normal operating motor ID to the clock hands. The hour and minute hands are designated by reference characters l6 and i1, and the 50 second hand by l8. As viewed from the back in Fig. 1, these hands will all rotate counterclockwise. The terminal shaft IQ of the motor It] will be assumed to rotate at one revolution per minute and drives a gear 20 in the direction indicated. 55 Gear 20 meshes with a similar gear 2| connected to the second hand shaft through a friction clutch 22. This clutch slips only when the second hand is held stationary by the stop catch indicated at 23. Gear 20 also drives a larger gear 60 which, in the example given, will have twice as many 5 teeth as gear 20 and will, therefore, rotate at onehalf revolution per minute. Gear 40 rotates freely on the minute hand shaft 24 of the clock which extends through the entire mechanism represented from the minute hand I! to the stop catch disc 25 at the rear of the clock. Secured to and extending from the face of gear 40 are two shafts 26 and 28. These shafts are equally distant from and on opposite sides of the central minute hand shaft 24. Rotatively mounted on shafts 26 and 28 are similar pinions 29 and 30. Ordinarily the two pinions shown on the same shaft will constitute a single pinion but, in the illustration, the parts arespread apart for better illustration. In any event, if two pinions 29 or 30 are used on the same shaft 26 or 28, they will be secured together on the same hub so as to rotate together about shafts 26 or 28. These pinions mesh with gears 58 and 6B which reference characters also designate, in the example given, the numbers of teeth in these two gears.

Gear 60 is secured to the minute hand shaft 2t and gear 58 is secured to,a hollow shaft 3| rotatively mounted on shaft 24. These two epicyclic gear arrangements form a diflerential. In normal operation gear 58, constituting one member of the diiferential, is held stationary and, since gear Ell has two more teeth than gear 58 and the pinion shafts 26 and 28 are rotated with gear 0 at one-half revolution per minute, gear 68 and the minute hand shaft 24 will be driven counterclockwise at 1/60 revolution per minute which is the correct rate and direction for the minute hand. The hour hand It is driven 1/720 revolution per minute from the minute hand shaft 24 through the usual back-gearing arrangement consisting of gears 9, 2'1, 8 and 32. The above constitutes the normal clock-driving arrangement.

Gear 58, which is normally stationary, is rotated when it is desired to set the minute and hour hands ahead or back. The hollow shaft M on which gear 58 is secured may be turned in either direction manually or by the synchronous motors I l and [2. For manual setting, a bevel gear 33, which is splined on hollow shaft 3|, is engaged by a second bevel gear 34 secured on the key shaft lb. The key shaft l5 and gear 3 are normally withheld from driving relation with bevel gear 33 by a spring 35 but may be pressed inward to driving engagement in the manual setting operation. The key shaft I5 will extend to a point adjacent the side wall of the'casing of the clock where it may be engaged by a sultablekey from the outside by some authorized person.

In Fig. 2, the plug 58 represents a closure opposite the end of key shaft I5, which'plug, when removed, allows a key to be inserted to move shaft I5 endwise to driving position and also to be turned for manually setting the hour and minute hands of the clock.

For automatic setting of the clock hands, the gear 36 is provided, which gear is connected in driving relation with the hollow shaft 3| by a friction clutch, part of which is represented in dotted lines at 31. 3'! represents a friction washer which is pressed against the side of gear 36 by the spring 88' acting through the hub of gear 43 which is splined to hollow shaft 3|. Gear 38 is in driving relation with the common terminal shaft 39 of the two synchronous motors I I and I2 through gear 4I. Since these motors are normally stationary, the gear connection normally holds gear 36 and gear 58 stationary. The friction clutch at 31 slips to allow rotation of gear 58 during a manual setting operation and also serves an additional purpose, which will be explained hereinafter.

Synchronous motors II and I2 are designed to operate in opposite directions. Their rotors are mounted on the same shaft. Synchronous motor I2, when energized alone, drives the terminal shaft 39 in one direction and synchronous motor II, when energized alone, drives the terminal shaft 39 in the opposite direction. To illustrate practicable values, it may be assumed that the normal speed of terminal shaft 39 is thirty revolutions per minute and that the gear relation is such as to normally drive gear 58 at 3% revolutions per minute during an automatic clock-setting operation. It will be observed that by reason of the diiferential connection either manual or automatic clock setting may be accomplished while the normal clock-driving motor I0 is in operation. During automatic clock-setting operations, the forward setting of the clock hands will then be slightly faster than abackward setting because, in setting the hands forward, the forward rotation due to the normal drivingmotor I0 is added and, in setting the hands backward, this normal movement is subtracted from the movements imparted to the clock hands from the synchronous resetting motors. For the gear relations and speeds previously given, the minute hand of the clock will be set ahead at the rate of one revolution in 18.6 seconds and set back at the rate of one revolution in 19.1 seconds by the synchronous resetting motors when the normal clock motor I0 is in operation. If the normal clock motor is stopped during an automatic setting'operation, the forward and backward setting rates will be exactly the same. In either case, it'will be evident that the clock hands exclusive of the second hand may be quickly set ahead or back without interfering with or being interfered with the normal operating parts of the clock drive whether the latter be in operation or otherwise. It will also be observed that the normal clock driving motor III might be a springv motor controlled byan escapement without changing the clock setting features.

To set all of the clocks of a system so that their indications are identical, the magnet latch device I3 is provided and it may be used alone or .secured to a shaft which is in combination with. the clock-setting motors, depending upon the results desired. The magnet latch consists of afield magnet having an energizing coil and provided with an air gap in which is located an armature 42. The armature is secured to a rotatable shaft 43 which carries a latch 44 adjacent a latch disc 25 on the minute hand shaft 24, and also a latch 28 which extends through a small opening in the clock face (see. Fig. 2) adJacent the 60 minute position of the secondhand I8. Means such as a spring 45 is provided to bias the shaft 43 to the rotary position shown where the latches 44 and 23 are withdrawn from their latching positions and where the armature 42 is in a position to be 15 rotated when its field of its magnet is energized. A stop indicated at 46 limits the movement of the shaft in the deenergized position. When the magnet I3 is energized, its armature 42 rotates to a minimum reluctance position in the air gap 20 .and brings latch 44 into engagement with theedge of disc 25. Disc 25 is provided with a notch 41 which preferably is opposite latch 44- when the minute hand is oppositethe 12 o'clock position. Thus when'this magnetic latch device is 25 energized, the minute hand will be stoppedin the 12 oclock position the next time'it arrives at such a position. When the magnetic latch is energized the catch 23 also moves into the path of the second hand I8 and stops the same as 30 the second hand reaches the 60 second position. At first sight, it would appear that, when-the minute hand shaft is stopped by the latch 44 entering notch 41, the normal driving motor I0 would be stopped from further rotation and that, 35 consequently, the second hand I 8 might not reach the 60 second position. Such is not the case as neither of these pointer stopping operations block the operation of motor I!) or its drive to the pointer which is last to stop. When the minute 49 hand shaft is stopped by latch 44, gear 40 rotates gear 58 and gear 60 stands still, this being per.- mitted by reason of difierential connection and the slipping of the clutch 31 between hollow shaft 3| and gear 36. When the second hand is' ifi.

' latch magnet is energized by either of the synchronous setting motors I I or I 2 or by the manual setting device. Following a hand stopping operation the latch magnet Isis deenergized, spring 45 withdraws the latches from their'stopping positions and the pointers immediately start and move normally. The utility of these features 55 will be clearer when the system of Fig. 3 is explained.

The clock may also be. provided with the electromagnetic signal'device I4 to indicate interruptions in the source of supply to motor I0 when the latter is an electricmotor. 'I'hisdevicecom sists of a small magnetic armature 48 located in the air gap of .a magnet which derives its fiux from the field of motor III. Thearmature 48 is rotation in a clockwise direction by a weight 48. This rotary movement is limited by stops 50 and -5I. The shape of the armature 48 is such that,

when the field is energized,the armature has two positions of minimum reluctance, one position 70 being as represented; The other position of biased for limited pole pieces or the magnet. The sector. 49 has two diflerently colored portions, such as red and white, which colors alternately appear in an opening 52 in the clock face (see Fig. 2) when the armature 48 is turned from one position of minimum reluctance to its other position of minimum reluctance. The stop Il may be pushed inward by hand by inserting a suitable tool through an opening in the side wall of the clock casing to move the signal and armature from the position shown to its other position above mentioned. The opening in the clock casing for this purpose is normally closed by a water-tight plug indicated at 53 in Fig. 2. The stop 5| when released returns to the position shown by reason of the spring 54.

The operation .of this device is as follows: When the motor I is energized, armature 48 is initially manually positioned so that the dotted line axis of the armature aligns with the field pole pieces and the sector 49 is raised somewhat from the position shown. So long as the motor remains energized, the signal will be held in this position by the field flux and the white color 0! the sector 39 will appear in the opening 52 in the clock dial. If now the source of supply to motor it) fails, the signal shaft will rotate by gravity into approximately the position shown, bringing the red color on sector 49 in the clock face opening 52. Even though the source of supply is restored, the signal will remain in this position because this is also a position of minimum reluctance of its armature $8. The signal will thus indicate that there has been a failure in the source of supply and that the clock probably needs resetting before its time indication can be relied upon. When the clocl; is corrected, the signal should be manually reset to its original position.

The circuit connections to the cloclr. are preferably carried through a water -tight conduit ll the cloclr casing such as is represented at 55, Fig. 2.

in Fig. 3, I have represented a clock system and control circuits for use with clocks of the character shown in Fig. 1. The electrical devices of two such clocks are indicated in Fig. 3 by the same reference characters as were used for the corresponding devices in Fig. 1. The normal driving motors id of the clocks will be connected to a suitable source of alternating current supply 56, the frequency of which is accurately regulated so as to distribute time. The synchronous cloclr-setti'ng motors ii and it will be connected to suitable control circuits leading to a control point and a suitable source of alternating current supply. This source is indicated at It may be the same as source 56 but it is unnecessary that its frequency be regulated for time accuracy. The source of supply for the magnetic clutch devices i3 may be either direct or alternating current. As represented, I use the source 5? for this purpose. One side 59 of source 5i goes directly to one terminal of all of the clocksetting motors, and to one terminal of all of the magnetic latch clock-stopping devices. The other terminals of all of the clock-setting motors ii, which are used for forward setting or" the different clocks, are connected to a common con' trol line 6! and a switch 62 in order that they may be simultaneously connected to and disconnected from the other side of the supply source 51. These motors are thus controlled as a group.

Likewise, the remaining terminals of all of the clock-setting motors l2, which are used for a backward setting of the different clocks, are connected to a common control line 63 and a switch 64 so as to be started, stopped, and controlled as a group. The magnetic latch or clock-stopping devices are all connected 'by wire 65 and control switch 68 into a third control group. These control switches will ordinarily all be located at one control point and, if more than one control point is desired, a duplicate set 01' control switches connected in parallel with the set shown can be used at such other control point.

While I have shown a system embodying only two clocks, it is to be understood that ordinarily, where such a system is used, a much larger number of clocks will be included in the system and be subject to the group control outlined above.

It will be observed that the control switches 62 and 64 are biased against back contacts by springs and that these back contacts may be connected to a source of direct current represented by a battery 58. This direct current source may be utilized for quickly bringing the synchronous clock-setting motors to a stop following a clocksetting operation. It will be observed that with the auxiliary switch 69 leading to the battery 68 closed and the control switches 62 and (it in the positions shown, a direct current will circulate through all of the field windings of the various clock setting motors. This is indicated by the arrow heads in the connections associated with the setting motors for the clocls nearest the control point. The rotors for the motors ii and i2 are mounted on the same shaft and both turn when either motor is operated. Consequently, a very reflective magnetic braking action occurs when direct current is circulated through the field windings of these motors following a clock-setting operation which quickly brings the motors to a stop and prevents the scattering which might otherwise occur due to possible difierent coasting periods of difierent motors. Thus, to set the clocks ahead, the switch 59 is closed and switch 62 pressed upward. This energizes motor group ii with alternating current from source 57? with motor group i2 deenergized. The motors are selfstarting and of a type that start and reach synchronous speed almost instantaneously. Obviously, there is no scattering of these motors when operating synchronously. When the clocks are set ahead the desired amount, switch 02 is released, motor group H is deenergized and both motor groups it and it are almost instantaneously energized by direct current and stop almost instantaneously.

To set the clocks back, switch 66 is closed upward. This opens the direct current circuit and energizes motor group it from source 51. When the clocks are set the desired amount, switch ti t is released and both motor groups are energized with direct current as before to exert a powerful magnetic braking action on both groups of motors ii and i2.

The switch tit is used whenever it is desired to set all the clocks to a specified hour indication or to bring all the clocks to given indication to assure that they are all alike previous to a, clocksetting operation.

The following examples are given in order to make clear the more important uses or" the resetting control. Assume (I) that all the clocks are in synchronism and register 3:07. If it is desired to set all of the clocks to 5:00, switch 62 is closed until the clocks have been set ahead beyond 4:00 and then the stop magnet switch 86 is closed. Close switch 62 again and all of the clocks will be setahead to, :00 where they second stopping point.

will all bestopped b'ythe catches 44 and 28.. The switch 68 should be closed for at least 60 seconds after the minute hands have stopped in order to give all of the second hands time to reach the 6 Assume (2) that the clocks are out of synchronism, that one registers 3:07: and another 3:25, and it is desired to set all to 8:15. Press the setahead switch 62 to close until the slowest clock registers within 60. minutes .of 8:00. Then; close the stop switch as and again close the set-ahead switch 62 until all clocks have'reached and been stopped at 8:00. The clocks are now in synchronism; Now close the magnetic braking switch ,69, if it is not already closed, open the locking switch-66, and again closathe set-ahead switch 62 until the clocks register 8:15.

' It will be apparent that, with-the arrangemen described, there will be no noticeableseattering of the minute hands in the final setting operation above described after they have been synchronized at the 8:00 position. Also the second hands will be in synchronism as they all start 011" together when the lock switch 66 is opened and this synchronous relation of the second, hands is not interfered with by the operation of the clock-setting motors and I2. The second hand may be set to any exact second during a sixty-second interval by energizing the magnetic stop detdce to stop the second hand and then deenergizing the magnetic stop circuit at theproper instant during such interval.

'Suppose the clocks are two minutes and thirty seconds fast and it is desired to correct the same. This may be accomplished by first closing switch 59 to assure magnetic braking and quick stopping of the resetting motor and then close switch 65 upward momentarily until the minute hands are corrected. Switch 69 should then be reopened to prevent waste of energy. Then close switch 68 to energize the magnetic stop devices and stop the second hands for thirty seconds. The clocks are now correct as it will be. evident that the stopping of the second hand does not stop the minute handsunless the latter happen to be at the exact 12:00 o'clock position. The order of correcting I the minute and second hands just mentioned might be reversed with the sameresults.

When a clock is out of synchronism by more than an'hour,- the hour hand needs attention, and it is necessary to set it ahead orback to within the 60 minute automatic clock setting range with 5 the other clocks byhand, after which it can be exactly synchronized and setwith the other clocks automatically from the control station.

The clock apparatusand system above described is particularly useful on ocean-going vessels where it is necessary to reset the clocks ahead and back frequently. It is particularly useful for the clocks on naval vessels and large aircrafts where it essential that clocks at difierent points on a vessel and on the different vessels of a fleet be synchronized for gun fire and'navigation control, etc.

What I claim as new and desire to secure by Letters Patent of the United States, is:-

1. An electric clock comprising clock hands, a

' clock motor, a drive train between said motor and clock hands through which the clock hands are normally driven at a time-keeping rate, said drive including a differential, one portion of which is normally stationary, and a pair of clocksetting" motors connected to drive the normally stationary part of saiddifierential in opposite aoaaees back at a rate appreciably faster than the timekeeping rate and without interfering with the normal operation of said first mentioned motor.

2..A clock comprising hour, minute, and sec- 5 and hands, a clock motor connected to normally drive said hands-at'the time-keeping rates indicated,a diflerential, the drive to the hour. and minutehands being through said diflerential, one part of which is normally held stationary, a pair 1Q of normally idle synchronous motors for driving the stationary part of said differential in opposite directions for rapidly setting the hour and minute hands ahead or back while the first mentioned motor is driving said second hand at its normal 15 rate, and electrically controlled means for stopping the minute and second hands in predetermined positions upon their arrival at such positions without stopping said first mentioned motor.

3. An electric clock comprising hour, minute, and second hands, a clock motor for normally driving said hands at the rates indicated, a difi'erential included in the drive to the hour and minute hands, one part of which is normally held stationary, a slip friction clutch, a pair of normally idle clock-setting motors connected to the. normally stationary part of said difierential through said slip friction clutch for rapidly setting the minute and hour hands forward or backward, another slip friction clutch between the first mentioned motor and second hand, and means for stopping the minute and second hands in predetermined positions as they arrive at such positions without stopping said first mentioned motor.

4. An electric clockcomprising hour, and min-" ute hands, a clock motor for normally driving said hands at the rates indicated, a differential,

said drive being through said difierentiai, one part of which is normally held stationary normally disengaged manual, meansfor rotating the normally stationary part of said differential for setting the clock hands, a pair of normally in active synchronous motors for rotating the normally stationary part of said difierential for automatically setting the clock hands in either'45 direction, and a slip friction clutch between said last mentioned motors and the normally stationary part of said diiferential.

5. An electric clock including minute and sec- 1 0nd hands, a synchronous motor, separate driving tion continues to be driven by said motor after the other hand has been stopped."-

6. An electric clock including a minute hand and a second hand, a synchronous motor, separate driving connections between said synchronous motor and hands for normally driving said hands at the rates indicated, an electromagnetic latch mechanism which when energized causes the minute hand to be stopped-in a predetermined position upon its arrival thereat, said mechanism .70 also including means for stopping the second hand in a predetermined position upon its arrival at such position, and slip friction means associated with the drive for the minute hand which permits said motor to continue to drive the secacaasss 5 ond hand to stopping position after the minute hand has been stopped.

7. In a device having a rotary indicating hand, a pair of self-starting synchronous motors connected in driving relation with said hand, one motor when energized alone driving the hand in one direction and the other motor when energized alone driving the hand in the opposite direction, a source of alternating current, control circuits for separately energizing said motors from said source, a direct current source and means for connecting said motors in series to said direct current source for quickly stopping the same following a hand-setting operation.

8. In a device having a rotary indicating hand, a pair of self-starting synchronous motors connected in driving relation with said hand, one motor when energized alone driving the hand in one direction and the other motor when energized alone driving the handin the opposite direction, a source of alternating current, a control circuit including a switch having a position for energizing one of said motors from said source, a control circuit including a switch having a position for energizing the other motor from said source, and a direct current source, said switches having other positions for connecting said direct current source in series relation with said motors.

9. In a clock system including a plurality of clocks, means for synchronously setting the minute and hour hands of the cloclrs comprising, in each clock, a pair of normally idle self-starting synchronous motors having their rotors connected on a common shaft and respectively connected to drive the clock hands in opposite directions at an appreciably higher rate than normal, an alternating current source, a control circuit for connecting only one of the motors of each pair in a group to said source for setting all the clocks in one direction, a control circuit for connecting only the other motors of each pair in a group to said source for setting all the clocks in the opposite direction, and means for simultaneously energizing both groups of motors over said control circuits for magnetic braking purposes to quickly stop the same immediately following a clock-setting operation in either directlon.

13. In a clock system having a plurality of clocks, meansior synchronously setting the minute and hour hands thereof comprising, in each clock, a pair oi normally idle sell-starting syn chronous motors having their rotors mounted on a common shaft and connected to drive the clock hands at an appreciably higher rate than normal without otherwise interfering with the normal operation of said clock, one motor of each pair loeing connected to drive the clock hands clockwise and the other motor 01 each pair being connected to drive the clock hands counterclockwise, a source of alternating current supply, a control circuit for energizing only the clockwise setting motors of all the clocks in a group from said source, a control circuit for energizing only the counterclockwise setting motors in a group from said source, a direct current source and means iorsirnultaneously energizing the motors of both groups over aid control circuits to quickly stop the same immediately following a clock-setting operation in either direction.

11. A clock system including a plurality of clocks each provided with hour, minute and second hands and normally active means for synchronously driving the clock hands at the rates indicated, means for quickly setting the hands of all said clocks to any desired indication in case their time indications are different by not more than an hour comprising, in each clock, normally inactive synchronous motor means connected to drive the minute and hour hands in either direction at a rate appreciably faster than nor mal without otherwise interfering with the normally active clock driving means, also, in each. clock, a normally inactive electromagnetic stop device which when energized stops the minute hand and the second hand at predetermined minute and second indications which are similar in the difierent clocks, when said hands arrive at said indications without otherwise interfering with the normally active means for driving said hands, a source of alternating current supply, control circuits including switches, selective as to the direction of clock setting, for connecting the synchronous motor clock-setting means of all or" said clocks to said source, and a control circuit including a switch for energizing the electromagnetic stop devices of all clocks.

HENRY E. WARREN. 

